By SAM ROBERTS

Published: March 21, 1992

Gov. Bill Clinton, gliding toward the Democratic nomination, today begins his campaign in New York, where he needs not only to defeat Edmund G. Brown Jr. decisively on April 7 but to lay the groundwork for victory next November in a pivotal state that no Democratic nominee can afford to lose.

The quest for New York's 244 delegates could become a sideshow to what will be the main event for Mr. Clinton: to repair his relationship with some local Democrats, including Gov. Mario M. Cuomo, and to win over black, Jewish and Hispanic voters and organized labor in a state where he is little known. Teachers' Endorsement Set

"It's important not only for the primary," said Harold M. Ickes, the New York campaign manager for Mr. Clinton, who is to scheduled to announce the endorsement of the New York State United Teachers union at its convention in Manhattan today and formally accept support from black and liberal members of Congress.

Albert Scardino, the Clinton campaign spokesman in New York and the former press secretary to Mayor David N. Dinkins, said, "I don't know that it's so much to repair relationships as to build them."

Mr. Ickes said the Arkansas Governor would spend much of the next two weeks in New York trying to transform his overwhelming organizational support into votes and reaching out to groups that he needs next month and in November. He expects to begin television advertising a week to 10 days before the primary.

"Clinton has an opportunity to spend some time here so that, one, he gets to know the state, and, two, it helps him in the fall," said John A. Marino, the Democratic state chairman. "People say New York is a given for a Democrat, but that's not the history of this state. Four years ago by this time my mother was sold on Dukakis. She's not sold on Clinton."

In 1988, Michael S. Dukakis's decisive victory in the New York primary catapulted him to the nomination, but he only squeaked by George Bush in the state in the general election. No Democrat since Harry S. Truman in 1948 has been elected President without winning New York. Haunted by Candidates Past

This year, the campaign is haunted not only by the ghost of campaigns to come, President Bush, but by the ghost of campaigns past, the Rev. Jesse Jackson, and the ghost of a campaign that might have been, Mr. Cuomo.

New York's spectral primary ballot will list the names of three Presidential candidates who have already withdrawn from the race, Senator Tom Harkin of Iowa, Senator Bob Kerrey of Nebraska and former Senator Paul E. Tsongas of Massachusetts. Two other candidates on the ballot, Lawrence A. Agran, the former Mayor of Irvine, Calif., and former Senator Eugene J. McCarthy of Minnesota, have yet to graduate, as Mr. Brown did this week, from a protest candidate to a potential spoiler.

New York may also present Mr. Brown with an unusual opportunity to uncouple the potent biracial coalition of blue-collar voters that Mr. Clinton successfully forged elsewhere, in part by invoking the name of Mr. Jackson.

Mr. Brown's own name may not be on the New York ballot, though, unless he survives a legal challenge still being pursued by the fringe New Alliance Party, which lost the first round. If he does, New York could be his last stand. Ron Brown, the Democratic national chairman, has hinted that if the former California Governor loses Tuesday in Connecticut and two weeks later in New York, Wisconsin and Kansas, he should abandon his campaign. Labor Backing for Brown

In sharp contrast to Mr. Clinton, who has been organizing in New York for months, Mr. Brown is bereft of any formal campaign apparatus in New York State. The telephones at his headquarters, a spare room behind a tie manufacturer's showroom on Park Avenue, were turned on only Thursday and there were so few of them there that the campaign manager, Jeffrey Myhre, was working from home yesterday.

But Mr. Brown arrives already armed with endorsements from several politically potent local labor leaders, including Jan Pierce of the communication workers and Barry Feinstein of the teamsters, with more likely. That support, combined with Mr. Brown's invitation to Mr. Jackson to join him as a running mate, could erode the coalition that Mr. Clinton fashioned in earlier primary states. Mr. Brown is tentatively scheduled to campaign in Harlem tomorrow.

In New York's 1988 Presidential primary, Mr. Jackson carried New York City and came in second statewide, capturing 37 percent of the vote in a five-man field. Blacks accounted for about one in four votes cast four years ago. If turnout in other states is any indication, their proportion will probably shrink this year without Mr. Jackson on the ballot. But Mr. Brown may benefit from his repeated effort to associate himself with Mr. Jackson a strategy that Mr. Jackson has barely discouraged. 'Grateful to Governor Brown'

"He is grateful to Governor Brown for having the confidence in his ability, experience and accomplishments to say he would put him on the ticket," said Frank Watkins, Mr. Jackson's spokesman and the political director of Mr. Jackson's political organization, the Rainbow Coalition. "Clearly, he is gratified that Governor Brown thinks that highly of him. In 1984 and 1988 many of the candidates and party leaders were running away from Jackson and clearly it's better to be pursued than to be chased."

The state's two leading black elected officials, Mayor Dinkins of New York and Representative Charles B. Rangel of Harlem, say they expect to remain neutral in the primary campaign.

Another prominent black official, Representative Major Owens of Brooklyn, who originally supported Mr. Harkin, is to endorse Mr. Clinton formally today.

So is Representative Ted Weiss, whose district covers the West Side of Manhattan where a prominent political club, the Park River Independent Democrats, has endorsed Mr. Brown.

Mr. Marino, the party state chairman, said, "If he's able to put together a coalition of labor, environmentalists, liberals, anti-Clinton people and if he's able to add another group -- like African-Americans -- he may do very well, by which I mean better than Michigan." Mr. Brown got 26 percent of the vote in Michigan. Building Campaign Apparatus

For months, though, Mr. Ickes has been building a campaign apparatus that includes most downstate Democratic county chairmen and an eclectic group of public officials, including Ruth W. Messinger, the Manhattan borough president, who described Mr. Clinton yesterday as "the person who can beat George Bush and will beat him with a perspective that brings people together across race lines and works on behalf of cities."

But Mr. Cuomo's decision last December not to run for President and the withdrawal of several candidates since then has left a vacuum that some New York Democrats say neither Mr. Brown nor Mr. Clinton have yet filled.

On Thursday, the executive board of Local 1199 of the hospital workers union decided to endorse no one for the time being.

Mr. Cuomo has predicted that Mr. Clinton would emerge as the nominee but has squabbled with him in the past and has so far refrained from endorsing a candidate.